Lubricating oil composition



Patented Aug. 4, 1942 UNlwED STATE LUBEICATING OIL COMPOSITION Franklin,M. Watkins, Chicago, 11]., asaignor to Sinclair Refining Company, corporation of Maine No Drawing. Application October 11, 1940,

New York, N. Y., a

Serial No. 360,743 v a 18 Claims. (Cl. 252-35) My invention relates to improvements in compounded petroleum lubricating oils. More particularly, this invention relates to improvements in liquid petroleum lubricants as distinguished from solid or semi-solid petroleum greases. The improved lubricating-oil compositions of my invention consist essentially of a petroleum lubricating oil and a metal salt of an alkyl mono-ester of an alkenyl substituted succinic' acid, or a mixture of a normal and a basic metal salt of an ankyl mono-ester of an alkenyl substituted succinic acid, in amount, or amounts, insumcient materially to alter the normal liquid character of the petroleum lubricating oil itself. The term petroleum lubricatingoils is intended to refer herein to-lubricating oils of petroleum origin having viscosities upwards of about 50-70 seconds Saybolt Universal at 100 F.

The trend of development in internal combustion engines has imposedjncreasing burdens upon the oils used and their lubrication, particularly with respect to operating temperatures and pressures. At present, the Diesel type of engine probably represents extreme requirementsin both of these respects, but itis not alone in the m position of severe burdens upon the lubricating oil used. The useful operating life of a lubricating oil in such service is determined in large measure by its thermal stability and by its physical capacity to continue functioning as a lubricant at the. high temperatures and high pressures encountered. One measure of thermal stability is resistance to oxidation, and the consequent tendency to form sludge, but in another aspect the effect of thermal instability is determined not only'by the extent of oxidation or de= composition but also by the character of the products of such decomposition or oxidation and by the extent and location, within the engine, of deposits of such products. I

The improved lubricating oil compositions of my invention have, in addition to the lubricating properties of the petroleum oil of which they are high temperatures to which the lubricatingoil is subjected, particularlyat the top of the stroke, frequently causes deposition of sludge and car-. -bonization in the groove for and behind one or more of the piston rings. v lubricating oils such difllcultles are usually more Using paraflinic type pronounced with respect to the uppermost ring; using naphthenic type-lubricating oils they are usually more monounced with respect to the lower rings. Conmquent sticking oi the rings rapidly deprives the pistons and cylinder wall of proper lubrication inducing excessive wear and, frequently, scoring of the cylinder wall. The formation of such "carbon deposits, hard enough and coherent enough to involve sticking of the rings, is materially retarded, if not avoided, by

' economical with respect both to loss of service time and cost, for the many otherwise necessary cleaning and repair jobs.

The class of metal salts of alkyl mono-esters of an alkenyl substituted succinic acid compounded with a petroleum lubricating oil with efiective results in accordance with my invention may be represented by the following isometric structural 3o formulae:

compounded, a high solvent capacity for sludge,

In this aspect, the lubricating oil compositions of my invention render the engines in which they are used self-cleaning to an important extents In the Diesel type of engine, for exa .iple, the" CHr-COOR' wherein R is an alkenyl group, R is an aliryl group, and X is a metalin the form of a normal or basic sa1t.- By "alkenyP is meant a hydrocarbon-group containing a double-bond, such, for example, as the hydrocarbons produced by polymerization oi olefins, although other hydrocarbon groups containing a double-bond from other sources maybe used. The laurenyl groupparticularly effective in accordance with my invention, the calcium being present either as the normal salt or as the basic salt, or a mixture of the normal and basic salts may be used. However, the corresponding salts of other metals may be used with advantage to produce the improved compounded lubricating oil of the present invention. For example, aluminum, barium, cadmium, chromium, magnesium, nickel, 'stannous tin, and zinc salts of alkyl mono-esters of alkenyl substituted succinic acid may be'used with eflective ester of the alkenyl substituted succinic acid of my invention may be formed by the reaction between the mono-ester mono-sodium salt and a is filtered to remove unreacted calcium hydroxide, and the benzene is removed by distillation up to a final temperature 01' 250 F. under a vacuum corresponding to about 4 mm. of mercury. The residue from this distillation comprises the basic calcium salt of the lauryl mono-ester of laurenyl succinic acid apparently in the form of a mixture of the normal and the basic calcium salts of the lauryl mono-ester of laurenyl succinic acid. The basic calcium salt thus produced (comprising a mixture of the normal and basic calcium salts) contains about 6.3% calcium by weight .with only a trace of sodium.

metal salt (such for example as calcium chloride). The basic metal salt may be prepared by liberating the free mono-acid, mono-succinic ester and by reacting this free acid in anhydrous benzene with a substantial excess of metal hy-' droxide (such for example as calcium hydroxide).

It must be understood, however, that the metal salts used in accordance with my invention are not limited to this particular mode of preparation and include such metal salts as are described herein regardless of their source and method of preparation. a 4 l The 'basic calcium salt or the lauryl monoester of laurenyl succinic acid for compounding an exampleof the improved lubricating oil compositions of my invention can be produced as follows: equimolar parts by weight of dodecene (a trlmer of iso-butylene) and maleic anhydride are heated for about 4% hrs. at 400 F. under a super-atmos'phericpressure. The reaction product is placed in a still and the unreacted dodecene and maleic. anhydride are distilled 01! up to aflnal temperature of 450 F. at '60 mm. pressure. The dodecene and maleic anhydride thus removed by distillation are then reacted together for a second reaction period of about 4 hours at a temperature of about 420-430 I". under super-atmospheric pressure, and the resulting reaction product is again distilled to remove unreacted dodecene and maleic anhydride. The combined yield from these two reactions,- totaling upwards of about 50% and obtained as the still residues from the two distillations, has theappearance of areddish viscous oil and comprises laurenyl sucsodium and lauryl alcohol are then reacted together and are suspended in benzene. One moleccinic anhydride having a saponiflcation number of 392. One molecular weight each of metallic ular weight of the laurenyl succinic anhydride is then added to this benzene sodium-sodium laurylate mixture. The mixture is refluxed for about 3 hours, sodiumis washed out of the re,- iluxed mixed with aqueous acid, and the benzene is distilled from thisproduct. The benzene-free product comprises the lauryl mono-ester of laurenyl succinic acid and has an acid number of about 117.5. The basic calcium salt is then pre pared by heating a benzene solution of the lauryl mono-ester of laurenyl succinic acid with a large excess (about five mols to one) of calcium hydroxide. The mixture is refluxed for about two hours at 30 F. The resulting benzene solution The preparation of a normal calcium salt 0 an alkyl mono-ester of an alkenyl substituted succinic acid may .be effected by the following methodof obtaining, by way of example, the normal calcium saltof the butyl mono-ester of laurenyl succinic acid. Laurenyl succinic anhydride is reacted with an equimolar proportion of sodium 'butylate in boiling benzene solution to form the sodium salt of butyl mono-ester of laurenyl succinic acid. An aqueous alcohol solution of calcium chloride is then added with vigorous stirring with the resulting formation, by a double decomposition reaction, of the normal calcium salt of the butyl mono-ester of laurenyl succinic acid. The benzene solution of this normal calcium salt is then washed with water to remove alcohol and inorganic salts (sodium chloride). The washed benzene solution is then flltered and is heated under sub-atmospheric pressure to remove benzene and any alcohol and water remaining in the benzene solution. The

resulting normal calcium salt of the butyl monoester of laurenyl succinic acid is' a dark colored waxy solid material containing 5.13% calcium. This normal calcium salt may be transformed into the corresponding basic calcium salt by agitating the normal calcium salt with hydrochloric acid and by then adding a large excess (flve mols to one) of calcium hydroxide and refluxing this mixture with benzene. Excess calcium hydroxide is removed by filtration and benzene is removed by distillation. The resulting basic calcium salt of the butyl mono-ester of laurenyl succinic acid is a dark, brittle, resinous product containing about 8% calcium by weight and appears to comprise a mixture of about 55% of the basic calcium salt and about 45% of the normal calcium salt of the butyl mono-ester of laurenyl succinic acid.

In compounding the improved lubricating oil compositions of my invention with Pennsylvania, Gulf Coast or Mid-Continent petroleum lubricating oils, including such oils which have been solvent refined, the metal salt of an alkyl monoester of an alkenyl substituted succinic acid, or a mixture of these metal salts, is added to the lubricating oil in amounts ranging from about 0.5% up to about 2.5% or 3% by weight on the oil, or even higher. Within this range I have found that amounts of these metal salts corresponding to about 1%% by weight on the oil are particularly eflective. The basic calcium salt of the lauryl mono-ester of laurenyl succinic acid,

prepared as described above, is completely soluble to the extent of by weight in a Gulf ing oil and upwards of 8% by weight in a Mid- Continent lubricating oil. salt of the butyl mono-ester of laurenyl succinic acid and the basic calcium salt of the butyl mono-ester of laurenyl succinic acid, both prepared as described above, are also readily soluble to the extent of at least 1 by weight in Gulf Coast, Mid-Continent and Pennsylvania lubricating oils but are soluble only to the extent of approximately 1% in a double solvent refined Pennsylvania oil.

As an example of a liquid lubricating oil composition of my invention, a composition consisting essentially of a South Texas pale oil (a Gulf Coast oil), having a viscosity of about 500 seconds at 100 F. Saybolt Universal and boiling up to 700 F. and 90% up to 900 F., ap-

proximately, and 1 by weight on the oil of a" basic calcium salt of the lauryl mono-ester of laurenyl succinic acid, produced as described hereinabove, is particularly advantageous. The stability of this lubricating oil composition, as shown by the "Indiana Oxidation Test described in the S. A. E. Journal 34, 172-173 (1934) is much greater than the stability of this South Texas base oil alone. The Indiana Oxidation Test sludging time with the base oil was 17.0 hours as compared to 26.5 hours for the compounded lubricating oil composition thus representing an increase of about 56% in the sludging time for the compounded oil. In service in a Diesel type engine, this lubricating oil composition left the engine free from sludge or carbon deposits except for a slight discoloration of the piston just above the lower compression rings and a small amount of carbon on the anti-thrust side of the uppermost ring groove of the piston and adequately The neutral calcium acid, prepared as described hereinabove, in-

creased the sludging time, determined by the Indiana oxidation test, by about 10% in the case of a South Texas oil having a viscosity index of 12.4 and by 106% in the case of a Pennsylvania lubricating oil having a viscosity index of 102.5,

, on the oil in each instance.

lubricated the moving parts of the engine. The

properties of this particular lubricating oil composition, as compared to those of the lubricating oil alone, as determined in one instance, were as follows:

While the lubricating oil composition of the foregoing example embodies specifically a South Texas (Gulf Coast) lubricating oil, other-lubricating oil compositions of my invention embodying petroleum lubricating oil from paraffin base crudes, asphaltic base crudes and mixed base crudes are useful. For example, about 1%% by weight of the basic calcium salt of the lauryl mono-ester of laurenyl succinic acid, prepared as described hereinabove, increased the sludging time in the Indiana oxidation test by 61% in the case of a Mid-Continent medium-heavy oil having a viscosity index of 77.9 and by 143% in the case of a Pennsylvania-type lubricating oil having a viscosity index of 102.1. salt f the butyl mono-ester of laurenyl succinic The neutral calcium the neutral calcium salt-being incorporated in these oils to the extent of about 1 by weight The basic calcium salt of the butyl mono-ester of laurenyl succinic acid, prepared as described above, increased the sludging time by 48% in the case of the same South Texas lubricating oil having a viscosity index of 12.4 and by 151% in the case of the same Pennsylvania lubricating oil having a viscosity index of 102.1, the basic calcium salt also being incorporated in these oilsto the extent of about 1 /a% by weight on the oil in each instance.

The metal salts of alkyl mono-esters of an alkenyl substituted succinic acid, being readily soluble in petroleum lubricating oils having high viscosity indices as well as in petroleum lubricating oils having low viscosity indices, are effective anti-sludging compounds of wide applicability to oils obtained from difierent sources and having either high or low viscosity indices. These metal salts do not materially alter the physical properties of the lubricating oils with which they are compounded, do not causejelling of the 'compounded oils, and do not increase the pour point of the base oils with which they are compounded.

The compounded lubricating oils of my invention stituted succinic acid, the metal being selected from the group consisting of calcium, aluminum, barium, cadmium, chromium, magnesium, nickel, stannous tin, and zinc.

2. A liquid lubricating oil composition comprising a petroleum lubricating oil and a metal salt of an alkyl mono-esterof laurenyl succinic acid, the metal being selected from the group consisting of calcium, aluminum, barium, cadmium, chromium, magnesium, nickel, stannous tin, and zinc.

3. A liquid lubricating oil composition comprising a petroleum lubricating oil and a calciumsalt of an alkyl mono-ester of an alkenyl substituted succinic acid.

4. A liquid lubricating oilcomposition comprising a petroleum lubricating oil and a calcium salt of an alkyl mono-ester of laurenyl succinic acid.

5. A liquid lubricating oil composition comprising a petroleum lubricating oil and a calcium salt of an alkyl mono-ester of succinic acid, said acid having substituted therein a trimer of isobutylene.

6. A liquid lubricating" oil composition comprising a petroleum lubricating oil and a calcium salt of an alkyl mono-ester of the product obtained by reacting maleic anhydride and an olefin at an elevated temperature under pressure.

'7. A liquid lubricating oil composition comprising a petroleum lubricating oil and a mixture of normal-and basic calcium salts of the lauryl, mono-ester of. an alkenyl substituted succinic acid.

'8'. A liquid lubricating oil composition comprising a petroleum lubricating oil and a calcium salt of the lauryl mono-ester of. an alkenyl substituted succinic acid.

9. A liquid lubricating oil composition com-= prising a petroleum lubricating oiland a basic calcium salt of the 'laurylmono-ester of an alkenyl substituted succinic acid.

10. A liquid lubricating oil composition. comprising a petroleum lubricating oil and a mixture of normaland basic calcium salts of the butyl.

mono-ester of an alkenyl substituted succinic acid. v

11. A liquid lubricating oil'composition com. prising a petroIeum lubricating oil and a calcium salt ofthe butyl mono-ester of analkenyl substituted succinic acid.

12. A liquid lubricating oil composition com-. prising a petroleum lubricating oil and a basic calcium salt of the butyl mono-ester of an alkenyl substituted succinic acid; p

13. A liquid lubricating oil composition comprising a petroleum lubricating oil and a mixture of normal and basic calcium salts of the lauryl mono-ester of laurenyl succinic acid.

14. A liquid lubricating oil composition comprising a petroleum lubricating oil and acalcium salt of the lauryl mono-ester oflaurenyl succinic acid.

15.. A liquid lubricating oil composition comprising a petroleum lubricating oil and a basic calcium salt ofthe lauryl mono-ester oflaurenylsuccinic acid.

16. A liquid lubricating oil composition comprising a petroleum lubricating-oil and a mixture of normal and basic calcium salts of the butyl calcium salt of the-butyl mono-ester of laureny'l succinic acid. W FRANKLIN M. WATKINS. 

